A technology of increasing a record capacity through an optical disc has been developed and has widely been spread. Furthermore, the recording capacity of the optical disc is tended to be more highly dense. For example, an optical disc having a recording capacity of 8.5 gigabytes called DVD-9 and recorded from both surfaces for each layer in a double layer structure has been produced. A manufacturing method of such a kind of optical disc as described above is such that two sheets of disc substrates are formed on which mutually different information is recorded by means of two molding machines and reflective films having different reflectivities are formed on their corresponding recording surfaces by means of two sputtering devices and disc substrates are adhered together with mutual recording surfaces faced with each other. The reflective films have two alternative cases of using two different kinds of reflective materials for the reflective film to achieve different reflectivities and of varying a thickness of the same material reflective film to achieve different reflectivities.
On the other hand, there is another optical disc on one surface of which a one layer is recorded and having the recording capacity of 4.7 gigabytes. In this case, one disc substrate on which an information is already recorded and another disc substrate on which an information is recorded are formed by means of two molding machines and, thereafter, the reflective film is formed only on the recording surface by means of a single sputtering device. Then, there are two cases in which no reflective film is formed on the disc substrate having no recording surface and in which another sputtering device is used to form the reflective film whose reflectivity is different from that of the one optical disc substrate on which the recording surface is provided. These two disc substrates are adhered together. In such an optical disc as a Digital Versatile Disc (DVD) or Compact Disc (CD), the disc substrates are manufactured by e. g., molding machines. However, a considerable heat is used to soften a resin material during the molding. A temperature of the disc substrate outputted from the molding machine is high. Hence, the reflective film needs to be formed by means of a sputtering device after the temperature is reduced to a normal temperature. This cooling is carried out at a process at which the disc substrates from both molding machines are disposed in a plane form on respective receipt tables of carrying mechanism generally straightly moved and a cooling wind is blown over the disc substrates. Consequently, this mechanism becomes large sized and there is a possibility of adhering a dust on an upper surface of the disc substrates. In addition, two film forming devices such as sputtering devices are prepared at a process in which two sheets of disc substrates from the step at which different reflective films are formed and two sheets of disc substrates on which the reflective films whose reflectivities are different from each other by means of their corresponding film forming devices are carried to a transfer device and the two sheets of disc substrates are overlapped on the transfer device and overlap device. However, since a distance by which the two sheets of optical disc substrates are moved becomes long and there is a high possibility of adhering a dust on the upper surfaces of the disc substrates. In addition, an occupied area of the dust cannot be small but also requires the time in carrying the disc substrates. It is noted that since an accurate read of the information cannot be achieved when a dust or the like is adhered on the adhering surface of each disc substrate, the adhering of the dust on the adhering surface of each disc substrate needs to be avoided. Although this problem can be solved if the manufacture is carried out in a clean room, it is practically difficult to carry out the manufacture in the clean room with a cost and other production line taken into consideration. In either case, in a conventional manufacturing device, the carrying mechanism itself, transfer mechanism itself, and a combination of these mechanisms has different points even if the molding machine in which the single machine simultaneously manufactures two kinds of disc substrates and film forming device such as a sputtering device in which the single machine can form two kinds of reflective films is used or not used. A carrying line from the molding process of disc substrates to an overlapping process is so long that it takes a lot of time. Hence, there is a high possibility of adhering a dust onto the disc substrates. In addition, the carrying line cannot be small sized.